1. Field of the Invention
This invention relates to treatment of contaminants in the environment so that they do not contaminate the liquid in a container, more particularly, a liquid to be used in an assay in an automated clinical analyzer.
2. Discussion of the Art
The members of the ARCHITECT® family of automated diagnostic analyzers, commercially available from Abbott Laboratories, require fluid handling systems that employ at least one sub-system for aspirating and dispensing samples and reagents, at least one sub-system for dispensing buffers, at least one sub-system for dispensing pre-trigger fluids and trigger fluids, and at least one sub-system for handling liquid waste.
Through aspiration processes, samples are moved from sample containers and assay reagents are moved from reagent containers for dispensing into reaction vessels. In addition, wash buffer is dispensed for priming and flushing. Trigger solutions and pre-trigger solutions are also dispensed into reaction vessels. Trigger solutions and pre-trigger solutions are normally stored on-board the automated diagnostic analyzers as bulk liquids in relatively large containers.
Bulk liquids are typically aspirated from containers, such as, for example, bottles, and the volume of liquid aspirated is displaced by air from the atmosphere surrounding the automated diagnostic analyzer, through a vent in a straw assembly. As a result, carbon dioxide, i.e., CO2, from the atmosphere surrounding the automated diagnostic analyzer is absorbed by and dissolved in the bulk liquid, and the pH of the bulk liquid, namely the trigger solution, is lowered. The stability of the trigger solution when stored upon the automated diagnostic analyzer is approximately two weeks. After two weeks, the amount of carbon dioxide absorbed by and dissolved in the trigger solution lowers the pH of the trigger solution to a level that results in adversely affecting results of an assay.
EP 0 766 087 discloses a method for the detection of creatinine in which an aqueous solution containing creatinine is contacted with a dry reagent system containing an indicator for creatinine at a pH above about 11.5. The high pH is provided by a dry alkaline material upon its being hydrated by the aqueous fluid. The dry reagent is packaged with a material capable of absorbing carbon dioxide and at least some ambient water vapor. The carbon dioxide-absorbing material is provided in an amount sufficient to substantially inhibit the formation of carbonic acid in the area of the reagent system. This inhibition of the production of carbonic acid increases the shelf life of the creatinine-detecting device by reducing or eliminating the neutralization of the alkali reagent by carbonic acid formed in situ.
U.S. Pat. No. 6,218,174 discloses degassing by driving a gas-containing solution to sub-atmospheric pressure approximately equal to the solution vapor pressure, and maintaining the subatomic pressure not withstanding evolution of gas from the solution. This method may be accomplished using a vacuum tower arrangement whereby a column of gas-containing liquid is drawn to the maximum physically attainable height. So long as the vacuum is coupled to the liquid column above this height (generally on the order of 34 feet, depending on the ambient temperature and the composition of the liquid), the liquid will not be drawn into the vacuum, which creates a non-equilibrium region of extremely low pressure above the liquid that liberates dissolved gases.
U.S. Pat. No. 7,329,307 discloses a carbon dioxide removal system including a member having a first opening and a second opening to enable air flow and containing lithium hydroxide (LiOH) supported by the member and having an initial water content above an anhydrous level. U.S. Pat. No. 7,329,307 further discloses removal of carbon dioxide by including pre-hydrated LiOH adsorbent in a location having air flow with carbon dioxide. The carbon dioxide is removed with pre-hydrated LiOH adsorbent.
Accordingly, it is desired that the useful life of the trigger solution be extended as much as possible, so that the entire contents of the container of the trigger solution can be consumed prior to the date by which it has deteriorated excessively. It is further desired that the trigger solution have a useful life of at least about two weeks, and preferably longer, after being exposed to air in the atmosphere surrounding the automated diagnostic analyzer. It is still further desired that the pH of the trigger solution be maintained at the appropriate level for an extended period of time.